Disposable infusion device with air trapping collapsible reservoir

ABSTRACT

A wearable infusion device delivers a liquid medicant to a patient. The infusion device comprises a reservoir arranged to contain a liquid medicant to be delivered beneath a patient&#39;s skin. The reservoir has an outlet through which the medicant flows and a shape that forms at least one pocket that traps air isolated from the outlet. The infusion device further includes a conduit communicating with the outlet of the reservoir, and a pump that causes the medicant to flow from the reservoir into the conduit.

BACKGROUND OF THE INVENTION

Tight control over the delivery of insulin in both type I diabetes(usually juvenile onset) and type II diabetes (usually late adultonset), has been shown to improve the quality of life as well as thegeneral health of these patients. Insulin delivery has been dominated bysubcutaneous injections of both long acting insulin to cover the basalneeds of the patient and by short acting insulin to compensate for mealsand snacks. Recently, the development of electronic, external insulininfusion pumps has allowed the continuous infusion of fast actinginsulin for the maintenance of the basal needs as well as thecompensatory doses for meals and snacks. These infusion systems haveshown to improve control of blood glucose levels, however, they sufferthe drawbacks of size, cost, and complexity, which prevents manypatients from accepting this technology over the standard subcutaneousinjections. These pumps are electronically controlled and must beprogrammed to supply the desired amounts of basal and bolus insulin.

Hence, there is a need in the art for a simple, mechanically driveninfusion device for both basal needs and boluses that is directlyattached to the body and does not require any electronics to program thedelivery rates. The insulin is preferably delivered through a small,thin-walled tubing (cannula) through the skin into the subcutaneoustissue similar to technologies in the prior art. The present invention,in its various embodiments, is directed to providing such a device.

SUMMARY OF THE INVENTION

The invention provides a wearable infusion device comprising a reservoirarranged to contain a liquid medicant to be delivered beneath apatient's skin. The reservoir has an outlet through which the medicantflows and a shape that forms at least one pocket that traps air isolatedfrom the outlet. The device further comprises a conduit communicatingwith the outlet of the reservoir, and a pump that causes the medicant toflow from the reservoir into the conduit.

The reservoir shape includes at least one raised region forming the atleast one pocket. The raised region may comprise a pointed region havingconcave side walls.

The reservoir may formed of flexible sheet material having a seal line,and the raised region may be along the seal line. The reservoir shapemay include a plurality of the raised regions.

The reservoir shape includes at least a first raised region along afirst side and at least a second raised region along a second sideopposite the first side. One of the first and second raised regionsforms a pocket that traps air when the reservoir is disposed to placethe first and second sides in a plane having a vertical component.

In another embodiment, a wearable infusion device comprises a reservoirarranged to contain a liquid medicant to be delivered beneath apatient's skin, the reservoir being formed of flexible sheet materialjoined along a seal line, having an outlet through which the medicantflows and a shape that forms a plurality pockets that trap air isolatedfrom the outlet. The shape includes a plurality of raised regions alongthe seal line to form the pockets. The device further includes a conduitcommunicating with the outlet of the reservoir and a pump that causesthe medicant to flow from the reservoir into the conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The invention,together with further features and advantages thereof, may best beunderstood by making reference to the following description taken inconjunction with the accompanying drawings, in the several figures ofwhich like reference numerals identify identical elements, and wherein:

FIG. 1 is a perspective view of an infusion device embodying the presentinvention;

FIG. 2 is a perspective view of the device of FIG. 1 with its top coverremoved and in a condition ready for having its reservoir filled withliquid medicant;

FIG. 3 is a perspective view of the infusion device of FIG. 1 with itstop cover removed after its reservoir has been filled with liquidmedicant;

FIG. 4 is perspective view with portions cut away of the infusion deviceof FIG. 1 illustrating the path of the liquid medicant within thedevice;

FIG. 5 is a top view of the device of FIG. 1 with its reservoir removedto illustrate the manner in which the liquid medicant is caused to flowwithin the device;

FIG. 6 is a perspective view of the infusion device of FIG. 1 with itsreservoir removed illustrating further aspects of the pump thereof;

FIG. 7 is a perspective view of the infusion device of FIG. 1 withportions cut away to illustrate a safety check valve in its openedposition;

FIG. 8 is a perspective view similar to FIG. 7 illustrating the safetycheck valve closed;

FIG. 9 is a perspective view of a reservoir which may be used in theinfusion device of FIG. 1 in accordance with an alternate embodiment;and

FIG. 10 is a perspective view with portions cut away of the reservoir ofFIG. 9 illustrating further aspects thereof according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, it illustrates an infusion device 100 embodyingthe present invention. The infusion device 100 may be useful, forexample, in providing boluses of a liquid medicant, such as insulin, tobe delivered beneath a patient's skin.

The device 100 generally includes a base 110, a top cover 120, and acannula port 130. The base 110 prior to application to the patient'sskin, carries a first tab member 112 and a second tab member 114. Thefirst tab member 112, when removed, exposes a layer 116 of antisepticmaterial such as alcohol which may be rubbed against the skin of thepatient in the area in which the device 100 is to be adhered. Once theantiseptic has been applied to the patient's skin, the second tab 114 isremoved exposing an adhesive layer on the base 110 which is then used toadhere the device to the skin of the patient. Once the device is adheredto the skin of the patient, a cannula may be introduced into the deviceand beneath the skin of a patient through the cannula port 130.

As may be seen in FIG. 2, the device 100 further includes a pair ofactuator push buttons 120 and a reservoir 140 arranged to contain theliquid medicant. As will be seen hereinafter, concurrent pressing of theactuator push buttons 120 causes the liquid medicant within thereservoir 140 to flow down a flexible conduit 150 and eventually beneaththe skin of a patient. Each of the push buttons 120 are spring loaded byan associated spring 122 and 124 which return the push buttons 120 totheir starting positions.

The reservoir 140 as shown in FIG. 2 does not yet contain the liquidmedicant. A latch mechanism 160 precludes the push buttons 120 frombeing pressed when the reservoir 140 is empty. To that end, it will benoted that a follower bar 162 extends across the reservoir 140 andterminates at a latch member 164. A dog 166 is coupled to the pushbuttons 120 and engages the latch member 164 to preclude the actuatorbuttons 120 from being pushed when the reservoir is empty.

Referring now to FIG. 3, when the reservoir is filled as illustrated inFIG. 3, the follower bar 162 follows the expansion of the reservoir 140.To that end, the reservoir 140 is preferably formed of flexiblematerial, such as plastic, and will expand upon being filled. Thefollower bar 162 follows the filling of the reservoir 140 to raise thelatch member 164. When the reservoir is full, the latch member 164 israised to such an extent that the dog 166 may pass thereunder to permitthe push buttons 120 to be pressed to cause pumping of the liquidmedicant to the patient. Again, the springs 122 and 124 assist inreturning the push buttons 122 to a starting position.

The reservoir 140, as may be noted in FIG. 3, includes a plurality ofraised portions 142 formed along its perimeter. This reservoir shapecauses air pockets to be formed within the reservoir that traps airisolated from the reservoir outlet 144. Accordingly, the device 100 isintended to be worn with its major axis 102 horizontal. In such anorientation, air within the reservoir 140 may be trapped in the airpockets, such as air pocket 146.

Referring now to FIG. 4, it illustrates the fluid flow path of theliquid medicant upon being pumped responsive to the pressing of theactuator buttons 120. The fluid flow path is shown in dashed lines inFIG. 4. As maybe noted, the fluid flow from reservoir 140 begins at theoutlet 144 along a flexible conduit 148. The fluid medicant is propelledby a pump, such as a linear peristaltic pump 170 to be describedhereinafter. It first flows through a valve 180 which may be provided toisolate the pump 170 from the reservoir 140 when the pump 170 pumps thefluid medicant. The valve 180, under some circumstances, is optional, asfor example when a linear peristaltic pump of the type described hereinis employed as will be fully described hereinafter.

The fluid continues to flow along the flexible conduit 148 to eventuallyarrive at the cannula 200. It is then delivered to the patient beneaththe patient's skin.

FIGS. 5 and 6 show the peristaltic pump of the device 100 in greaterdetail. Here it may be seen that the peristaltic pump comprises a pairof pressure members 172 and 174. The pressure members 172 and 174 aredisposed on opposite sides of the flexible conduit 148. The direction offluid flow is indicated by the arrows 149 in a direction away from thereservoir (not shown). The pressure members 172 and 174 are spaced apartsuch that they become increasingly closer together in an upstreamdirection with respect to the fluid flow. Hence, when the pressuremembers 172 and 174 act upon the flexible conduit 148, they will serveto first pinch the flexible conduit closed and then, upon exertingadditional pressure, squeeze the conduit to force the liquid medicant inthe downstream direction.

As previously mentioned, the valve 180 is optional. If the pump utilizedis not a pump as illustrated herein that first closes off the conduit,the valve 180 may be coupled to the actuator buttons 120 so that thevalve 180 closes the conduit 148 before pressure is exerted on theflexible conduit 148 by the pump. To that end, the valve 180 includes afirst valve member 182 and a second stationary valve member 184. Valvemember 182 pivots about pivot point 186 upon the pressing of theactuator buttons 120 to pinch the flexible conduit closed against thestationary member 184.

In FIG. 6, it may be more clearly seen that each pressure member 172 and174 is integrally formed with an associated one of the actuator buttons120. More specifically, each pressure member may be formed as one piecewith its actuator button 120. Because the device 100 is intended to bedisposable, the actuator buttons and hence the pressure members 172 and174 may be formed of plastic.

Once the actuator buttons 120 are pressed and the peristaltic pump 170causes the liquid medicant to flow down the flexible conduit 148, theactuator buttons 120 are returned to their starting positions by theirrespective springs 122 and 124. At this point in time, the flexibleconduit 148 is charged with fluid to cause the fluid medicant to exitthe cannula 190 as illustrated in FIG. 4. To guard against back pressurewithin the cannula 190 and flexible conduit which would otherwise lessenthe amount of liquid medicant received by the patient, a check valve 190is provided. The check valve 190 is downstream from the pump 170 andperforms at least two functions. Firstly, the check valve 190 whenclosed precludes back flow of the medicant and assures that the medicantwithin the flexible conduit from the check valve to the cannula 200 iseventually diffused into the patient. It also precludes unintendedleaking of the liquid medicant into the patient in between actuations ofthe push buttons 120.

With particular reference to FIGS. 7 and 8, in FIG. 7, it will be notedthat the valve 190 is formed by a closing member 192 which is coupled toan actuator push button 120 at an attachment point 194. When theactuator buttons 120 are concurrently pressed, the closure member 192slides to the position indicated in FIG. 7 to an opened position topermit fluid flow through the flexible conduit 148. As may be seen inFIG. 8, when the actuator buttons 120 are released, the closure member192 is caused to move in a direction towards the flexible conduit 148and eventually pinches the flexible conduit 148 closed between theclosure member 192 and a stationary wall 196. Once the valve 190 isclosed as shown in FIG. 8, liquid medicant will not be permitted toinadvertently drip from the reservoir, flow through the conduit, and bedelivered to the patient.

Referring now to FIGS. 9 and 10, they show an alternative flexiblereservoir which may be used in the infusion pump according to theinvention. The flexible reservoir 240 is formed of flexible sheetmaterial including a sheet 242 and a sheet 244. The sheet materials 242and 244 are sealed along a peripheral seal line 246. As may be clearlynoted in FIGS. 9 and 10, the reservoir 240 is shaped to form raisedportions 248 on one side of the reservoir and raised portions 250 on theopposite side of the reservoir. The raised portions 248 and 250 may bepointed regions having concave sidewalls. For example, pointed regions248 have concave sidewalls 249 and pointed regions 250 have concavesidewalls 251.

When the reservoir 240 is deployed in an infusion device, such asinfusion device 100 of FIG. 1, it may be disposed so that the raisedregions 250 and 248 are along a pane having a substantially verticalcomponent. With the reservoir 240 being disposed such that the raisedregions 250 are above the raised regions 248, air pockets, such as airpocket 253 will be formed within the reservoir 240. The air pocket 253is isolated from the outlet 256 to assure that no air will becomeentrapped in the liquid medicant being delivered to the patient.

Hence, as may be seen from the foregoing, the present invention providesa simple, mechanically driven infusion device that provides boluses ofliquid medicant, such as insulin, and which may directly attached to thebody of a patient. The device does not require any electronics todeliver or program the delivery of the medicant. The liquid medicant,such as insulin, may be delivered through a small cannula into thesubcutaneous tissue of the patient as is common in the art.

While particular embodiments of the present invention have been shownand described, modifications may be made, and it is therefore intendedin the appended claims to cover all such changes and modifications whichfall within the true spirit and scope of the invention as defined bythose claims.

1. A wearable infusion device comprising: a base having an adhesivesurface for adhering the device to a patient's skin; a reservoirarranged to contain a liquid medicant to be delivered beneath apatient's skin, the reservoir formed of flexible sheet material joinedalong a seal line, having an outlet through which the medicant flows anda shape that forms a plurality pockets that trap air isolated from theoutlet, the shape including a plurality of raised regions along the sealline to form the pockets; a cannula arranged to extend from the base tobeneath the patient's skin; and a pump in fluid communication with thereservoir outlet that causes the medicant to flow from the reservoirinto the cannula.
 2. The device of claim 1, wherein each raised regioncomprises a pointed region.
 3. The device of claim 2, wherein eachpointed region includes concave side walls.
 4. The device of claim 1,wherein the raised regions are along a common side of the reservoir.